[libcamera-devel] [PATCH v7] test: gstreamer: Add test for gstreamer single stream

[Laurent Pinchart]

Hi Vedant,

Thank you for the patch.

On Thu, Aug 12, 2021 at 04:10:30PM +0530, Vedant Paranjape wrote:
> This patch adds a test to test if single stream using
> libcamera's gstreamer element works.
> 
> Signed-off-by: Vedant Paranjape <vedantparanjape160201 at gmail.com>
> Reviewed-by: Paul Elder <paul.elder at ideasonboard.com>
> ---
>  .../gstreamer_single_stream_test.cpp          | 134 ++++++++++++++++++
>  test/gstreamer/meson.build                    |  19 +++
>  test/meson.build                              |   1 +
>  3 files changed, 154 insertions(+)
>  create mode 100644 test/gstreamer/gstreamer_single_stream_test.cpp
>  create mode 100644 test/gstreamer/meson.build
> 
> diff --git a/test/gstreamer/gstreamer_single_stream_test.cpp b/test/gstreamer/gstreamer_single_stream_test.cpp
> new file mode 100644
> index 00000000..040b1e7e
> --- /dev/null
> +++ b/test/gstreamer/gstreamer_single_stream_test.cpp
> @@ -0,0 +1,134 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (C) 2021, Vedant Paranjape
> + *
> + * ipa_interface_test.cpp - Test the IPA interface
> + */
> +
> +#include <iostream>
> +
> +#include <libcamera/base/utils.h>
> +
> +#include <gst/gst.h>
> +
> +#include "test.h"
> +
> +using namespace std;
> +
> +class GstreamerSingleStreamTest : public Test
> +{
> +protected:
> +	int init() override
> +	{
> +		/* Initialize GStreamer */
> +		GError *err_init = nullptr;

Let's use the libcamera coding style, this should be errInit. Same for
libcamera_src_.

> +		if (!gst_init_check(nullptr, nullptr, &err_init)) {
> +			g_printerr("Could not initialize GStreamer: %s\n",
> +				   err_init ? err_init->message : "unknown error");
> +			if (err_init)
> +				g_error_free(err_init);
> +
> +			return TestFail;
> +		}
> +
> +		if (!gst_registry_scan_path(gst_registry_get(),
> +					    std::string(libcamera::utils::libcameraBuildPath() +
> +							"src/gstreamer")
> +						    .c_str())) {

Let's use a local variable to make this a bit more readable.

		std::string path = libcamera::utils::libcameraBuildPath()
				 + "src/gstreamer";
		if (!gst_registry_scan_path(gst_registry_get(), path.c_str()) {

> +			g_printerr("Failed to add plugin to registry\n");

You need to call gst_deinit() here.

> +			return TestFail;
> +		}

This won't work if the libcamerasrc plugin is already installed on the
system, gst_registry_scan_path() will not add anything in that case. You
need to remove the plugin first. I've tested the following code:

		/*
		 * Remove the system libcamera plugin, if any, and add the
		 * plugin from the build directory.
		 */
		GstRegistry *registry = gst_registry_get();
		GstPlugin *plugin = gst_registry_lookup(registry, "libgstlibcamera.so");
		if (plugin) {
			gst_registry_remove_plugin(registry, plugin);
			gst_object_unref(plugin);
		}

		std::string path = libcamera::utils::libcameraBuildPath()
				 + "src/gstreamer";
		if (!gst_registry_scan_path(registry, path.c_str())) {
			g_printerr("Failed to add plugin to registry\n");
			gst_deinit();
			return TestFail;
		}

> +
> +		/* Create the elements */
> +		libcamera_src_ = gst_element_factory_make("libcamerasrc", "libcamera");
> +		convert0_ = gst_element_factory_make("videoconvert", "convert0");
> +		sink0_ = gst_element_factory_make("fakevideosink", "sink0");
> +
> +		/* Create the empty pipeline_ */
> +		pipeline_ = gst_pipeline_new("test-pipeline");
> +
> +		if (!pipeline_ || !convert0_ || !sink0_ || !libcamera_src_) {
> +			g_printerr("Not all elements could be created.\n");

cleanup() isn't called if init() fails, so you need to unref pipeline_,
but also libcamera_src_, convert0_ and sink0_ here. The last three
elements don't need to be unrefered in cleanup(), because
gst_bin_add_many() makes the pipeline take ownership of them.

gst_deinit() is also needed here.

> +			return TestFail;
> +		}
> +
> +		return TestPass;
> +	}
> +
> +	void cleanup() override
> +	{
> +		gst_object_unref(bus_);
> +		gst_element_set_state(pipeline_, GST_STATE_NULL);

I'd move this call to the run() function, just before the
/* Parse error message */ comment, as it shouldn't be executed if the
pipeline isn't playing.

> +		gst_object_unref(pipeline_);
> +		gst_deinit();
> +	}
> +
> +	int run() override
> +	{
> +		/* Build the pipeline */
> +		gst_bin_add_many(GST_BIN(pipeline_), libcamera_src_, convert0_, sink0_, NULL);
> +		if (gst_element_link_many(libcamera_src_, convert0_, sink0_, NULL) != TRUE) {
> +			g_printerr("Elements could not be linked.\n");
> +			gst_object_unref(pipeline_);

This will cause a double unref, as cleanup() will be called.

> +			return TestFail;
> +		}
> +
> +		/* Start playing */
> +		ret_ = gst_element_set_state(pipeline_, GST_STATE_PLAYING);

This can be a local variable.

> +		if (ret_ == GST_STATE_CHANGE_FAILURE) {
> +			g_printerr("Unable to set the pipeline to the playing state.\n");
> +			gst_object_unref(pipeline_);

Same here, double unref.

> +			return TestFail;
> +		}
> +
> +		/* Wait until error or EOS or timeout after 2 seconds */
> +		GstClockTime timeout = 2000000000;
> +		bus_ = gst_element_get_bus(pipeline_);
> +		msg_ = gst_bus_timed_pop_filtered(bus_, timeout,

Both bus and msg can be local variables. Otherwise, for bus_, you'd have
to initialize it to nullptr, or cleanup() will crash if one of the above
two conditions is false.

> +						  GstMessageType((uint)GST_MESSAGE_ERROR | (uint)GST_MESSAGE_EOS));
> +
> +		/* Parse error message */
> +		if (msg_ == NULL)
> +			return TestPass;
> +
> +		switch (GST_MESSAGE_TYPE(msg_)) {
> +		case GST_MESSAGE_ERROR:
> +			gstreamer_print_error(msg_);
> +			return TestFail;
> +			break;
> +		case GST_MESSAGE_EOS:
> +			g_print("End-Of-Stream reached.\n");
> +			return TestFail;
> +			break;
> +		default:
> +			g_printerr("Unexpected message received.\n");
> +			return TestFail;
> +			break;
> +		}

A blank line would be nice here.

> +		gst_message_unref(msg_);

This will never be called, as all the cases above return. Furthermore,
msg_ is leaked in all those cases. I'd remove the return statements, and
turn the next line into

		return TestFail;

> +
> +		return TestPass;
> +	}
> +
> +private:
> +	GstElement *pipeline_, *libcamera_src_, *convert0_, *sink0_;

One variable per line please:

	GstElement *pipeline_;
	GstElement *libcamera_src_;
	GstElement *convert0_;
	GstElement *sink0_;

> +	GstBus *bus_;
> +	GstMessage *msg_;
> +	GstStateChangeReturn ret_;
> +
> +	void gstreamer_print_error(GstMessage *msg)
> +	{
> +		GError *err;
> +		gchar *debug_info;
> +
> +		gst_message_parse_error(msg, &err, &debug_info);
> +		g_printerr("Error received from element %s: %s\n",
> +			   GST_OBJECT_NAME(msg->src), err->message);
> +		g_printerr("Debugging information: %s\n",
> +			   debug_info ? debug_info : "none");
> +		g_clear_error(&err);
> +		g_free(debug_info);
> +	}

We usually put functions before variables.

> +};
> +
> +TEST_REGISTER(GstreamerSingleStreamTest)
> diff --git a/test/gstreamer/meson.build b/test/gstreamer/meson.build
> new file mode 100644
> index 00000000..b99aa0da
> --- /dev/null
> +++ b/test/gstreamer/meson.build
> @@ -0,0 +1,19 @@
> +# SPDX-License-Identifier: CC0-1.0
> +
> +if not gst_enabled
> +    subdir_done()
> +endif
> +
> +gstreamer_tests = [
> +    ['single_stream_test',   'gstreamer_single_stream_test.cpp'],
> +]
> +gstreamer_dep = dependency('gstreamer-1.0', required: true)
> +
> +foreach t : gstreamer_tests
> +    exe = executable(t[0], t[1],
> +                     dependencies : [libcamera_private, gstreamer_dep],
> +                     link_with : test_libraries,
> +                     include_directories : test_includes_internal)
> +
> +    test(t[0], exe, suite : 'gstreamer', is_parallel : false)
> +endforeach
> diff --git a/test/meson.build b/test/meson.build
> index 3bceb5df..d0466f17 100644
> --- a/test/meson.build
> +++ b/test/meson.build
> @@ -11,6 +11,7 @@ subdir('libtest')
>  
>  subdir('camera')
>  subdir('controls')
> +subdir('gstreamer')
>  subdir('ipa')
>  subdir('ipc')
>  subdir('log')

-- 
Regards,

Laurent Pinchart